Backups

My desktop computer has 5 hard drives on it. The first two are for Windoze. The last three have Linux Distros on them. Two use the ext4 file system and one uses the btrfs file system. I would like to be able to back up the data on the three linux distros to an external drive and be able to read the backup from the Windoze system. I would also like to back up data, say like pictures, to the only one folder on the back up drive, like a Pictures Folder, and not erase other images. Say if I want to back up pictures from Linux 2 to the back up drive and then Linux 3 to the backup drive, I want the pictures to go into the pictures folder and not erase pictures already there. I want a collection of my pictures. Then, if I plug the backup drive into the Windoze system, I want to be able to read and download those pictures into the Windoze drive. I don't need to backup the complete Linux systems. Can someone give detailed instructions on how to do this. What software recommended and how to set it up so I can achieve my goals. Thank you in advance for your time and advice.